Your body carefully balances the sodium levels in the blood. The range for normal sodium levels is 135-145 millimoles per litre (mmol/L). Some people naturally have slightly high sodium levels in the blood – usually around 146-148 mmol/L.
A low level of sodium in the blood (also known as hyponatremia) is relatively common. A high level of sodium in the blood (hypernatremia) is much less common.
If you’re otherwise feeling well it’s quite possible the test result was due to a glitch in processing your sample, and the next reading may be normal. But higher levels of sodium in the blood that don’t come down do need further investigation.
Hyponatremia
Symptoms and causes of hyponatremia
Low sodium levels in the blood causes hyponatremia. This usually happens if you drink too much water in a short time.
The most common symptoms are:
- nausea
- vomiting
- headaches
In really serious instances, low sodium levels can cause the brain to swell leading to confusion, fits, comas and sometimes death, though this is rare.
Treating hyponatremia
Treatment for hyponatremia will depend on the underlying cause and may be as simple as adjusting your diet, drinking less water or stopping taking certain medications until sodium levels are restored. In more extreme cases a saline (salt) solution may be administered intravenously to gradually raise sodium levels to a safe level.
Hypernatremia
Symptoms and causes of hypernatremia
Hypernatremia is defined as a serum sodium level above 146 mmol/L.
Hypernatremia can be caused by:
- dehydration, from diarrhoea and vomiting or diuretics (usually water tablets given for high blood pressure)
- kidney problems
- a rare condition called diabetes insipidus, which affects the body’s ability to process water. This is a much less likely cause.
Symptoms of high sodium levels in the blood can include:
- thirst
- headache
- nausea and vomiting
- lethargy
- confusion
- seizures
- loss of consciousness / coma.
Treatment for hypernatremia
There are a number of ways to reduce sodium levels in your blood. These include staying hydrated, reducing your salt intake and exercising. You’ll find lots of information and help with all of these in the Healthy lifestyle pages on our website.
Answered by the Health at Hand nurses
Sources and further reading
Dehydration – Know your risk – AXA Health
Getting your salt intake right – AXA Health
Diet and nutrition centre - AXA Health
Useful resources
- World Action on Salt & Health
- FoodSwitch UK - free app to help making healthier choices easier
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